Nuclear, Particle, Astroparticle and Cosmology (NUPAC) Seminars
Exploring the Role of a Mush Compliant Region in Sombrero Uplift Above the Socorro Magma Body
Presented by Grant Block, UNM
Volcanic eruptions are among the most powerful and awe inspiring geologic processes on Earth and can rapidly eject large volumes of lava. Arc volcanoes such as Mt. St. Helens have been shown to erupt over 1 km^3 of lava, and super volcanoes such as Yellowstone can erupt over 1,000 km^3 of lava, in periods spanning just hours to months. Where this magma is stored, and how it moves through the crust before it erupts are topics of intensive research. Studying these problems helps us understand volcanic eruptions, and more generally, the physics of magma plumbing systems. Large mid-crustal magma bodies are uncommon systems, but are an ideal laboratory to study the motion of magma in the crust due to their size and relative ease of detection and measurement from the surface. They have been observed at multiple large volcanic complexes such as Long Valley California and the Altiplano-Puna region of Bolivia, and regions without volcanism such as Socorro, New Mexico. Mid crustal magma bodies such as these have been found to hold volumes of molten and partially molten magma and are studied via geologic, geodetic and numerical methods. In this talk, I will focus on numeric modeling efforts of the Socorro Magma Body (SMB) a large sill-like (pancake shaped) magma body located ~19km under Socorro, NM. The models probe a rare phenomena observed only at the SMB and Altiplano-Puna Magma Body (APMB) known as "sombrero deformation" in which a central region of surface uplift is surrounded by a broad region of surface subsidence. The causes of this pattern are uncertain, but suggest complex architectures, rheologies and pressurization histories. We propose a model explaining this pattern with a mechanically compliant network of crystals and molten magma called "mush" surrounding a pressurizing sill-like magma chamber. Our results show sombrero deformation can be caused by episodic pressurization of the chamber, when it is surrounded by a mush zone of sufficiently low viscosity. We also find the duration of sombrero deformation is strongly controlled by pressurization rate as well as mush zone viscosity. These findings may be applied to systems such as the SMB to help understand the role mush plays in crustal magma transport and storage and therefore its impact on volcanic systems.
2:00 pm, Tuesday, December 6, 2022
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